The invention relates to a safety belt apparatus in particular for motor vehicles comprising a safety belt and a belt tautener. The safety belt can be a two-point or three-point safety belt, with one belt part being led from the vehicle body via a lock to a belt winder and comprising a connection. element extending from the releaseable lock part to the body of the vehicle.
The purpose of the belt winder is to exert a force on the belt roller in the wind up direction by means of a spring mechanism in order that in the unbuckled state the safety belt is largely wound in and does not lie too loosely in contact on the passenger. The purpose of the unwind blocking apparatus is to stop the further drawing out of the belt when an attempt is made to draw it out rapidly or in accident caused accelerations after a slight further rotation of the belt roller at the latest. The belt tautener is provided at the belt winder in order to abruptly rotate the belt roller by so many rotations in the wind up direction in an accident caused acceleration that the safety belt, which at first lies loosely at the vehicle passenger, is tautened in such a manner that the passenger does not fall in into the loosely fastened belt and injure himself in doing so.
Belt tauteners which are particularly suitable for the purposes of the invention are known from EP 581 288 B1 and U.S. Pat. No. 5,553,803.
Whereas the belt tautener is normally separated from the belt roller by a coupling, it is abruptly coupled to the belt roller in the event of a triggering in order to be able to initiate the belt tautening. A problem exists in that after the completion of the belt tautening it should be possible for the belt to be drawn out unhindered from the used belt tautener so that the driver can more easily free himself from the belt after the accident. In addition, in the case where the belt roller can still rotate somewhat relative to the blocked unwind blocking apparatus when the belt is drawn out, it is important to maintain this limited rotational movement of the belt roller as it damps the forward movement of the passenger.
An object of the invention is to provide a safety belt apparatus with a belt tautener in which the triggered and operated belt tautener no longer exerts a disadvantageous influence on the desired movements of the belt roller after a triggering event and the subsequent tautening of the belt.
An idea of the invention is that the belt roller, which is rotationally fixedly coupled in the wind-up direction to the belt tautener shaft during the belt tautening, is decoupled from the belt tautener after completion of the belt tautening. The decoupling occurs when the draw out force on the belt exceeds the tautener force so that a definite draw-out rotational movement of the belt roller, which is desirable after an accident, is not hindered by the still working or already expended belt tautener.
It is advantageously provided that a reversal of the rotational direction of the belt roller and/or drive of the belt tautener disengages the coupling.
The coupling drive affects that the closing or the engaging respectively of the coupling takes place through the rotation of the belt tautener immediately after a triggering.
The conducting-in member ensures a particularly operationally reliable, unobjectionable actuation of the coupling.
Both the disc and also the coupling members and the coupling ring can be designed to be very flat and thus to require little space in the axial direction.
The ratchet wheel ensures that the conducting-in and conducting-out abutments rotate with the coupling during a triggering, but are however held firmly at the beginning and end of a triggering so that in connection with the rotation of the disc in the one or the other direction they can reliably carry out the conducting-in and conducting-out, respectively, of the coupling members.
The invention provides a constructionally favorable and very operationally reliable measure to enable a rotation of the ratchet gear in the wind-up direction against a limited resistance and to completely suppress a backwards rotating of the ratchet gear.
Particularly important are the rotational spring elements which are effective in the framework of the rotational play.
The coupling ring which represents the output member of the coupling is expediently integrated into the belt roller.
The cut-out is expediently covered over by the coupling drive, which is preferably formed by the ratchet wheel and the components which are arranged at it.
It is particularly advantageous when a limited rotational play, which is in particular enabled by a torsional bar, is present between the unwind blocking apparatus and the belt roller and which enables the belt roller to make several rotations, in particular three to four rotations, in the event of an accident caused drawing force at the safety belt in order that the falling forwards of the passenger into an inflated airbag is preferably damped accordingly. The torsion bar is thus plastically, that is, lastingly deformed during the rotation under accident caused forces.